Using our Bet Labs software, we tested Simmons’ theory to determine if his hunch is correct.

Rule No. 6 in Bill Simmons’ Playoff Gambling Manifesto: Beware of all dome teams playing outdoors, especially in cold weather. Simmons’ theory is that dome teams are soft and not capable of adjusting to the cold temperatures of postseason football.

Does the data backup the hypothesis?

Using the Bet Labs database, teams that play in a dome or a stadium with a retractable roof have gone 8-24 (25.0%) straight up (SU) in postseason games played outside since 2003.

In comparison, non-dome teams in outdoor road playoff games have gone 50-56 (47.2%) SU over the same span.

That is a significant difference in win percentage and one that holds up if we expand our sample.